1. Field of the Invention
The present invention relates to a complex image forming apparatus to print a multi-color image and a single color image using different printing engines. More particularly, the present invention relates to a complex image forming apparatus having an improved structure that integrates a thermal printing engine for forming a color image by heat and a laser printing engine that performs single-color printing.
2. Description of the Related Art
In general, image forming apparatuses, such as laser printers, ink-jet printers, facsimiles, or digital copiers, among other types of devices, comprise a single printing engine inside the image forming apparatus that prints either a single color or a multi-color image, but not both. Thus, in a single color (mono) laser printer, print quality is high and high-speed printing can be performed. However, multi-color printing cannot be performed.
On the other hand, in an ink-jet printer, multi-color printing can be performed. However, print quality is generally lower and printing speed is reduced. In consideration of these problems, a complex image forming apparatus that integrated different engines has been disclosed in U.S. Pat. No. 6,582,039, which issued on Jun. 24, 2003.
Referring to FIG. 1, a conventional complex image forming apparatus is shown that comprises a complex printer in which a laser printing engine I and a color ink-jet printing engine 2 are integrated into the same apparatus. The complex image forming apparatus transfers a paper 4 to either a first or second path 7 and 8 that form different paths. The different paths begin when first and second picking-up units 5 and 6 pick up the paper 4 from a single paper feeding cassette 3. The first and second picking-up units 5 and 6 are installed in the direction of arrow A to moves up and down in the conventional integrated printing apparatus. When the first picking-up unit 5 descends and feeds the paper 4 to the first path 7, the second picking-up unit 6 is separated from the first picking-up unit 5 so that the paper 4 cannot be fed to the second path 8. Alternatively, when the second picking-up unit 6 descends and feeds the paper 4 to the second path 8, the first picking-up unit 5 is separated from the second picking-up unit 6 so that the paper 4 cannot be fed to the first path 7.
As described above, the conventional complex image forming apparatus having the structure as described above, has a single-color laser printing engine and a multi-color laser printing engine such that a user can perform single-color high-speed printing and multi-color printing selectively. The conventional complex image forming apparatus, however, feeds the paper via different paths (one for single-color high speed printing and the other for multi-color printing), and therefore includes a separate paper feeding path and a picking-up unit. Thus, the structure of the conventional complex image forming apparatus is complex and both multi-color and single-color printing cannot be performed on the same paper.
In addition, when color is printed using an ink-jet printer, it takes a long time to both print and dry the printed paper to obtain high quality prints. If the multi-color printed side is touched before drying is complete, the image is irrevocably damaged. The quality of the image on printed paper is notably lower compared to a regular photograph, and the color of the printed image is subject to change over time.